Marine Weather and Tides
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
|Sunrise 5:57AM||Sunset 8:27PM||Sunday July 23, 2017 4:52 AM EDT (08:52 UTC)||Moonrise 5:10AM||Moonset 7:40PM||Illumination 0%|
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|ANZ531 Chesapeake Bay From Pooles Island To Sandy Point- 432 Am Edt Sun Jul 23 2017 |
Rest of the overnight..W winds 10 kt. Waves 1 ft. A chance of showers. Vsby 1 to 3 nm.
Today..S winds 5 to 10 kt. Waves 1 ft.
Tonight..S winds 5 to 10 kt. Waves 1 ft. Showers and tstms likely.
Mon..W winds 5 kt. Waves less than 1 ft.
Mon night..NW winds 5 kt. Waves less than 1 ft.
Tue..N winds 5 to 10 kt. Waves 1 ft.
Tue night..NE winds 5 to 10 kt. Waves 1 ft.
Wed..SE winds 5 to 10 kt. Waves 1 ft.
Thu..S winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms through the night. Winds and waves higher and visibilities lower in and near tstms.
|ANZ500 432 Am Edt Sun Jul 23 2017 |
Synopsis for the tidal potomac and md portion of the chesapeake bay.. Primarily light winds are expected with high pressure to the south through the remainder of the weekend. Scattered Thunderstorms are likely from this afternoon into tonight. A cold front will move through Monday with additional chances for showers and Thunderstorms, followed by high pressure Tuesday and Wednesday. The next frontal system will approach on Thursday. Small craft advisories may be needed Wednesday night and Thursday.
7 Day Forecast for Marine Location Near Tolchester CDP, MDHourly EDIT Help
Area Discussion for - Philadelphia/Mount Holly, PA  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxus61 kphi 230800|
area forecast discussion
national weather service mount holly nj
400 am edt Sun jul 23 2017
A frontal boundary extended from the southern great lakes to the mid
atlantic states this morning with one low pressure system south of
long island, moving seaward. Another low will follow tonight,
passing south of long island on Monday. The cold front will trail
down into yet another low over the DELMARVA peninsula Monday night.
Canadian high pressure builds down into the northeast united states
Tuesday and Wednesday. A cold front approaching from the northwest
late Thursday may be very slow to pass through the mid atlantic
states next Friday and Saturday.
Near term until 6 pm this evening
Quite a bit to talk about in the near term. Currently, MCS is
slowly propagating southward southeastward off the coast of
delmarva, but cells continue to develop via upwind propagation
processes on the southwest flank. A large shield of lighter
precipitation has developed to the north of the main convective
band, still providing a nice steady rain and anvil lightning to
far southern portions of the cwa. Meanwhile, showers continue
developing on the west side of chesapeake bay, aided by
convectively-induced perturbations moving through the southern
mid-atlantic region at this time. Have prolonged pops in this
region through the overnight hours to account for these trends. Farther
north, long-lived MCV is moving offshore south of long island,
which provided a fairly sizable swath of 0.5-2 inch(es) of rain
tonight from lehigh county eastward through
hunterdon somerset middlesex monmouth counties in new jersey.
This will be an important consideration with regards to
tonight's forecast (see next section).
The aforementioned perturbations will be moving offshore this
morning, and with convective overturning affecting much of the
area, see very little in the way of precipitation chances later
this morning. Cloud cover is going to hang tough, I suspect,
owing to some northeasterly flow that will seep into the region.
Kdix is indicating an outflow boundary from the aforementioned
mcv that is sagging slowly southward through central new jersey
(as of 230 am located generally from trenton to manasquan. Winds
become northeasterly to the north of this boundary, and dew
points are a few degrees lower. Higher-resolution model output
suggests this may continue southward to approximately the mason-
dixon line through a considerable portion of the day (at least
a chunk of the morning hours) - in addition, some showers may
develop along this boundary (as seen in the past hour). Models
are notoriously too eager with dissipating such boundaries or
returning them northward. As such, I bumped down dew points
considerably (around 3-5 degrees) north of the mason-dixon line
today and re-oriented the winds to a more northeasterly
direction for a longer duration for these areas as well.
Guidance is noticeably cooler with highs today, and this makes
sense given the current observational trends. Will be
interesting to see how much clearing, if any, occurs today.
Regarding convective potential, the next in a series of midlevel
perturbations moves toward the region this afternoon and
tonight, and with somewhat more focused large-scale ascent
downstream in a weakly to negligibly capped environment,
scattered to widespread convection should develop this afternoon
to our west. The timing of its approach to our region looks
rather late in the day, and held off on higher pops to mostly
the tonight period. However, some storms may move into the far
western CWA by late afternoon. With the approach of stronger
westerlies as a larger-scale trough begins to amplify today,
vertical shear profiles will continue to improve. Think the main
question today will be degree of instability, with remnant cloud
cover and outflow boundaries likely making model depictions of
the thermodynamic environment mere pipe dreams.
However, southwesterly flow to the south west of the area
should advect warm moist air northeastward, allowing boundary-
layer based parcels to attain CAPE values 1000-2000 j kg by
afternoon near south of the convectively-reinforced surface
boundary in the southern mid-atlantic. Where this boundary ends
up is anyone's guess (mine is south of consensus, based on the
past 24 hours of analysis). Should such instability materialize,
cape-shear parameter space is favorable for organized severe,
with downburst winds associated with bowing segments and or
mesovortices embedded within convective segments clusters the
main threat. Highly heterogeneous convective environment would
suggest that more organized (lengthier) lines of convection may
be hard to materialize, especially given the very moist boundary
layer hindering the development of somewhat stronger cold
pools. Cam guidance hints at such a scenario playing out, and
given pattern recognition and the past 24 hours as "analog
guidance", this increases confidence in at least the overall
mode of strong to severe convection this afternoon evening -
again, should the stronger instability pan out.
With pws 1.75+ inches (somewhat lower than the past 24 hours,
aided by somewhat drier midlevels and a southward push of the
convectively-induced surface boundary) and the potential for
strong updrafts should near-surface based instability
materialize, heavy rainfall is a threat with any of the stronger
Short term 6 pm this evening through 6 am Monday
Tonight's forecast could be metaphorically described as throwing
darts in the dark.
As convection from the west moves into the region overnight,
there is a clear signal from cam guidance of developing a
mesoscale convective vortex on the north side of the convection,
with larger-scale influence via a developing eastward-moving
surface low translating across the mid-atlantic during this
period (as the trough in the eastern ohio valley continues to
amplify). Some cam depictions (and even some of the coarser
guidance) produce very alarming QPF during this period (with 3
to 6+ inches indicated in a corridor generally between i-78 and
i-80) as the MCV trudges eastward. This seems way overdone, and
the cams have had a history of that in the past 24 hours.
The concern is that the thermodynamic support just will not be
there (or, alternatively, will set up farther south) since the
convection occurring the past few hours has displaced the
surface boundary to far southern virginia at this time. My
suspicion is that the higher side of the QPF distribution is a
low probability, but I suspect there will be a swath of heavy
rainfall totals (maybe 1-3 inches rather than 3-6) where
convective organization combines with large-scale support.
Regarding the latter, as the trough to the west amplifies, a
downstream 250-mb jet streak in new england provides substantial
upper-level divergence. Considerable warm moist air will be
lofted above the zonally- oriented convectively-reinforced
boundary ... Somewhere ... In the mid-atlantic region and
advected northward. Meanwhile, with antecedent heavy rainfall in
portions of the region (the lehigh to monmouth county corridor,
for instance), ingredients are in play for a flood event. Too
much uncertainty for a watch at this time, but flooding
potential is definitely a concern tonight. Stay tuned.
Temp forecast is a blend of met mav MOS with some addition of
cam 2-meter temperatures to account for effects from
Long term Monday through Saturday
500 mb: a trough crossing new york state on Monday reaches|
eastern new england Tuesday with ridging height rises to follow
Wednesday. The next trough... Complex... Moves into the northeast
usa for the end of the week
temperatures: calendar day averages about 5 degrees above normal Monday
near normal Tuesday through Thursday... And then may run several degrees
above normal Friday and possibly into the weekend.
Forecast basis: a 50 50 blend of the 00z 23 GFS nam MOS was applied
Monday-Tuesday (except mainly GFS mav tt td), then 00z 23 gfs
mex MOS Tuesday night before relying heavily on the 05z 23 wpc
d4-8 elements for Wednesday - Saturday.
Monday... Unsettled conditions into Monday evening. The frontal
boundary is expected to drift south through our area with
lingering shower and thunderstorm potential along and ahead of
the front. Precipitable water values should be decreasing slowly
from north to south... To on average 1.5 inches. Partial clearing
develops from north to south later at night, with patchy dense fog
possible. Pwat is modeled to decrease to 1.2 inches by Tuesday
Tuesday... The axis of a mid level short wave trough has passed by in
the morning with height rises expected. It should be drying out.
A fly in the ointment may be onshore flow and a sprinkle on the
Wednesday... Partly sunny, possibly after morning stratus or fog?
again there is some modeling hint of sprinkles on the coast.
Thursday... Warm air advection develops late in the day. Chance
of showers and isolated tstms late.
Friday... A chance of showers and thunderstorms with the next
cold front, especially morning.
Saturday... Hopefully dry weather returns but models are slowing
the front and possibly stalling it as a tricky complex mid
level pattern develops. One short wave passes to our northeast
while another digs to our west, building the atlantic ridge
westward and making southwest flow aloft tend to stall the
front. If that happens... Showers would be in our area.
Aviation 08z Sunday through Thursday
The following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.
Sub-vfr CIGS (with locally patchy fog as well) this morning
generally along and north of the mason-dixon line should slowly
improve toVFR in the 12z-15z time frame with northeast winds
5-10 kts. Thereafter, winds may become easterly or southeasterly
(or even transition to southwesterly this afternoon for a
time), remaining around 5-10 kts. Stray showers may occur this
morning, but best chances for precipitation are after 00z, where
scattered to widespread strong thunderstorms are expected to
move through the area. Erratic winds gusts are likely with any
Monday...VFR. A chance of showers and thunderstorms with
subVFR conditions along a cold front.
Monday night... Conditions lowering to MVFR and possibly ifr in fog
patches with clearing after a chance of evening showers and
Tuesday... MVFR and ifr conditions in morning stratus fog
Tuesday night through Thursday... MainlyVFR though some MVFR fog
or stratus possible Tuesday night and Wednesday morning.
Sub-advisory conditions are expected to continue through
tonight. Storms are in the forecast again tonight, and some of
these may be strong and will likely produce heavy rainfall.
Locally rough seas should be expected near precipitation.
Outside of any precipitation, seas will generally be 2-4 feet
with a northeast to east flow developing this morning veering to
the southeast tonight, generally 5-15 kts.
Monday through Thursday... No marine headlines are anticipated.
a moderate risk of rip currents is expected to continue through
today as the new moon combined with an underlying swell of 10-12
seconds is occasionally showing up in buoy observations (though
less so overnight so far).
Tides coastal flooding
We have issued another coastal flood advisory for this evening's
high tide for the atlantic coastal waters and for adjacent
portions of the coast of delaware bay, as the new moon combined
with increased onshore flow today should provide conditions at
least as favorable, if not somewhat more so, for minor coastal
flooding. With last evening's high tide, some minor flooding
occurred in most of this area (though generally below advisory
levels). Thus, with the somewhat higher forecasts observed with
this evening's high tide, an advisory seems warranted.
Abe month of july rainfall as of 1 am... 6.46",20th wettest in
the por dating back to 1922. July record 10.42" 1969.
Dew point readings at kdov continue to measure too high
compared to surrounding locations and should be treated as
unrepresentative of the area.
Hibernia pa and hamburg nj transmitters are off the air (lost
hibernia this evening around 0015z 23). Both have trouble
tickets. No known rts.
Phi watches warnings advisories
Nj... Coastal flood advisory from 7 pm this evening to 1 am edt
Monday for njz012>014-020>027.
De... Coastal flood advisory from 7 pm this evening to 1 am edt
Monday for dez002>004.
Synopsis... Drag 4a
near term... Cms
short term... Cms
long term... Drag 4a
aviation... Cms drag 4a
marine... Cms drag 4a
tides coastal flooding...
Weather Reporting StationsEDIT (on/off)  Help NOTE: Click on distance to see the station location on a map
|Stations||Dist||Age||Wind||Air Temp||Water Temp||Waves||Pressure||DewPt|
|TCBM2 - 8573364 - Tolchester Beach, MD||0 mi||52 min||W 9.9 G 12||77°F||85°F||1007.9 hPa (-0.7)|
|44043 - Patapsco, MD||8 mi||42 min||W 5.8 G 7.8||76°F||1 ft||1008 hPa|
|FSKM2 - 8574728 - Francis Scott Key Bridge, MD||15 mi||52 min||WSW 5.1 G 7||75°F||1007.4 hPa (-1.0)|
|CPVM2||17 mi||52 min||78°F||78°F|
|BLTM2 - 8574680 - Baltimore, MD||18 mi||52 min||WNW 1 G 5.1||75°F||86°F||1007.2 hPa (-1.0)|
|APAM2 - 8575512 - Annapolis, MD||20 mi||52 min||75°F||1007 hPa (-1.0)|
|44063 - Annapolis||20 mi||42 min||WSW 3.9 G 5.8||77°F||1 ft||1008.1 hPa|
|TPLM2 - Thomas Point, MD||24 mi||52 min||SSW 11 G 13||78°F||83°F|
|44057 - Susquehanna, MD||25 mi||42 min||W 5.8 G 7.8||76°F||1007.5 hPa|
|CHCM2 - 8573927 - Chesapeake City, MD||32 mi||52 min||SSW 1.9 G 2.9||75°F||87°F||1007.5 hPa (-0.6)|
|BSLM2 - Chesapeake Bay, MD||38 mi||142 min||S 1.9||66°F||1008 hPa||66°F|
|DELD1 - 8551762 - Delaware City, DE||43 mi||52 min||SW 1.9 G 5.1||75°F||82°F||1007.3 hPa (-0.3)|
|RDYD1 - 8551910 - Reedy Point, DE||43 mi||52 min||75°F||85°F||1007 hPa (-0.4)|
|DRSD1 - Delaware Reserve, DE||44 mi||82 min||SW 1.9||74°F||1008 hPa||73°F|
|CA2 - 8571892 - Cambridge, MD||45 mi||52 min||74°F||87°F||1008.4 hPa (-2.0)|
|44062 - Gooses Reef, MD||46 mi||42 min||SSW 7.8 G 9.7||78°F||1 ft||1008.3 hPa|
|WASD2 - 8594900 - Washington, DC||47 mi||52 min||SW 2.9 G 5.1||76°F||87°F||1007.3 hPa (-0.9)|
|SJSN4 - 8537121 - Ship John Shoal, NJ||47 mi||52 min||SW 14 G 15||76°F||82°F||1006.9 hPa (-0.4)|
Wind History for Tolchester Beach, MD(wind in knots) EDIT (on/off)  Help
Airport ReportsEDIT (on/off)  Help Click EDIT to display multiple airports
|Baltimore / Martin, MD||13 mi||55 min||SSW 4||10.00 mi||Overcast||75°F||73°F||94%||1008.1 hPa|
|Bay Bridge Field, MD||17 mi||67 min||S 3||7.00 mi||Overcast||77°F||75°F||94%||1007.8 hPa|
|Phillips Army Air Field / Aberdeen, MD||18 mi||1.9 hrs||W 4||10.00 mi||Overcast||75°F||72°F||94%||1007.7 hPa|
|Annapolis, United States Naval Academy, MD||20 mi||2 hrs||Var 3||10.00 mi||Light Rain||75°F||75°F||100%||1007.6 hPa|
|Baltimore, Inner Harbor, MD||20 mi||2 hrs||no data||mi||76°F||73°F||91%||1007.6 hPa|
|Baltimore, Baltimore-Washington International Airport, MD||22 mi||58 min||N 0||7.00 mi||Partly Cloudy||73°F||73°F||100%||1007.5 hPa|
Wind History from MTN (wind in knots)
|1 day ago||Calm||Calm||NW||N||Calm||SE||SE||SE||E||SE||E||SE||SE||S||Calm||Calm||SW||Calm||Calm||NW||NW||NW||NW|
|2 days ago||Calm||Calm||Calm||Calm||NW||E||SE||SE||SE||SE||SE||SE||SE||SE||S||Calm||Calm||Calm||Calm||SW||Calm||Calm||W||W |
EDIT RT Ports Option Weekend mode (on/off) (on/off)  Help One Week of Data
|Tolchester Beach |
Click for Map
Sun -- 12:40 AM EDT 0.23 feet Low Tide
Sun -- 05:47 AM EDT New Moon
Sun -- 05:57 AM EDT Sunrise
Sun -- 06:10 AM EDT Moonrise
Sun -- 07:31 AM EDT 2.26 feet High Tide
Sun -- 02:23 PM EDT 0.33 feet Low Tide
Sun -- 07:48 PM EDT 1.40 feet High Tide
Sun -- 08:24 PM EDT Sunset
Sun -- 08:39 PM EDT Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
EDIT (on/off)  Help One Week of Data
|Baltimore Harbor Approach |
Click for Map
Sun -- 01:42 AM EDT 0.00 knots Slack
Sun -- 05:23 AM EDT 1.29 knots Max Flood
Sun -- 05:47 AM EDT New Moon
Sun -- 05:58 AM EDT Sunrise
Sun -- 06:11 AM EDT Moonrise
Sun -- 08:51 AM EDT -0.00 knots Slack
Sun -- 12:06 PM EDT -1.17 knots Max Ebb
Sun -- 03:41 PM EDT 0.00 knots Slack
Sun -- 06:15 PM EDT 0.67 knots Max Flood
Sun -- 08:25 PM EDT Sunset
Sun -- 08:39 PM EDT Moonset
Sun -- 08:56 PM EDT -0.00 knots Slack
Sun -- 11:54 PM EDT -0.78 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Weather Map and Satellite Images(on/off)  Help
|Weather Map ||IR Satellite Image from GEOS|
GOES Local Image of Mid-Atlantic EDIT
Wind Forecast for Philadelphia/Mount Holly, PA (4,6,7,8)(on/off)  Help
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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.